[The pathophysiology of post-thrombotic syndrome]

The acute stage of venous thrombosis is characterized by an inflammatory process, therefore the term phlebitis is often erroneously equated with venous thrombosis. In most cases, however, the inflammatory reaction or phlebitis is a secondary phenomenon, associated with the process of fibrinolysis and phlebitis as a primary cause is rare. Postthrombotic sequelae such as edema, varicose veins and ulcers usually are late complications and can take a long time to develop. The primary cause of the postthrombotic syndrome is related to an injured venous wall, including damaged valves or stenosis due to incomplete recanalisation. The amount of damage is dependent on the extent of the primary thrombosis and the degree and rapidity of thrombolysis. When postthrombotic changes are suspected, functional evaluation can be performed with ambulatory venous pressure measurement in a foot vein or with the aid of non-invasive methods such as volumetry.